Stimulus-reinforcer contingencies and local behavioral contrast

Area of Science:

• Behavioral psychology
• Animal behavior studies

Background:

• Behavioral contrast is a phenomenon where the rate of responding on one schedule is affected by the rate of reinforcement on a different, concurrent schedule.
• Local positive contrast specifically refers to an increase in responding during a component of a multiple schedule when the other component's reinforcement is decreased.

Purpose of the Study:

• To investigate the mechanisms underlying local positive behavioral contrast in pigeons.
• To differentiate between operant and Pavlovian influences on behavioral contrast.

Main Methods:

• Pigeons were trained on multiple schedules of variable-interval reinforcement, requiring key pecks on an operant key and signaling components on a signal key.
• A yoked procedure delivered food on variable-time schedules without requiring key pecks to control for reinforcement delivery.
• One component remained constant (30-second schedule) while the other varied in duration and reinforcement.

Main Results:

• Operant-key responding during the constant component was largely unaffected by changes in the variable component.
• Signal-key responding during the constant component was highest at the component's onset and varied with the duration and reinforcement of the other component.
• Signal-key responding patterns aligned with predictions for local positive behavioral contrast.

Conclusions:

• The findings support the additivity theory of behavioral contrast.
• Pavlovian stimulus-reinforcer relations appear to be the primary driver of local positive behavioral contrast.